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XI. 
ON THE BRIGHT COLOURS OF ALPINE FLOWERS. 
By J. JOLY, M.A., Sc. D., F.R.S. 
[Read January 18; Received for publication January 20; Published 
Marcu 25, 1893.] 
Ty is admitted by all observers that many species of flowering 
plants growing on the higher alps of mountainous regions display 
a more vivid and richer colour in their bloom than is displayed in 
the same species growing in the valleys. That this is actually the 
ease, and not merely an effect produced upon the observer by the 
scant foliage rendering the bloom more conspicuous, has been 
shown by comparative microscopic examination of the petals of 
species growing on the heights and in the valleys. Such exami- 
nation has revealed that in many cases pigment granules are more 
numerous in the individuals growing at the higher altitudes. The 
difference is specially marked in Myosotis sylvatica, Campanula 
rotundifolia, Ranunculus sylvaticus, Galium cruciatum, and others. 
It is less marked in the case of Zhymus serpyllum and Geranium 
sylvatica ; while in Rosa alpina and Erigeron alpinus no difference 
is observable.’ 
In the following cases a difference of intensity of colour is, 
according to Kerner (‘“‘ Pflanzen Leben,” 11. 504), specially 
noticeable :—Agrostema githago, Campanula pusilla, Dianthus inodo- 
rus (silvestris), Gypsophila repens, Lotus corniculatus, Saponaria 
ocymoides, Satureja hortensis, Taraxacum officinale, Vicia cracca, and 
Vicia sepium. 
To my own observation this beautiful phenomenon has always 
appeared most obvious and impressive. It appears to have struck 
many unprofessional observers. Helmholtz offers the explanation 
that the vivid colours are the result of the brighter sunlight upon 
the heights. It has been said, too, that they are the direct chemical 
effects of a more highly ozonized atmosphere. The latter expla- 
1G. Bonnier, quoted by De Varigny, ‘‘ Experimental Evolutions,’’ p. 55. 
SCIEN. PROC. R.D.S., VOL. VII., PART I. L 
